Not Applicable
1. Field of the Invention
This invention relates generally to light direction control, and more particularly, to techniques for the dynamic control of light propagation direction.
2. Description of the Related Art
The use of electro-optic methods for light beam deflection has long been discussed. When an electric field is applied to a particular light transmission medium, the index of refraction of the medium undergoes a small change, leading to a small change in the direction of an output light beam. Electro-optic light beam deflection techniques have found only limited practical applications, largely because of limitations that result in poor performance. For example, the largest achievable deflection angle is very small, usually in the milliradian (mrad) range (one mrad≈0.057xc2x0) . Also, direction resolution is poor. Typical resolution is on the order of {fraction (1/10)}, that is, only about ten distinct directions within the deflection range can be resolved. For comparison, other standard light beam deflection methods, such as acoustooptical, can have a resolution on the order {fraction (1/1000)}.
The object of the present invention is to provide an electro-optic light beam deflection system that has a relatively large deflection angle and a substantially enhanced resolution.
One significant improvement of electro-optic light beam deflection technique is the use of new materials having electro-optic coefficients much higher than those for the materials used in the prior art. These highly-electro-optic-sensitive materials have not been used for light deflection because of their severely detrimental xe2x80x9coptical damagexe2x80x9d effects, the so called photorefractive process. The present invention provides methods for reducing and eliminating photorefractive effects in those materials, making them useful as electro-optic light deflection media. The methods include the use of a suppressing light source, external electric fields, and temperature control.
The second significant improvement is to use a multi-layer structure in the deflector medium based on second order electro-optic effects. Such second order electro-optic deflectors substantially increase the aperture of the deflection medium without the need for increasing the supply voltage. With increased aperture, the angular resolution of the light deflection system is correspondingly increased.
The third significant improvement is to construct a light beam deflection system comprising an electro-optic deflector as an initial deflector and a geometric optics lens system as a deflection angle amplifier. With a deflection angle amplification, the system deflection angle can closely approach xc2x190xc2x0.
Other objects of the present invention will become apparent in light of the following drawings and detailed description of the invention.